As an example of fluid pressure units of such kind, there is conventionally known one including a fixed displacement hydraulic pump, an adjustable speed motor for driving the hydraulic pump, an actuator, such as a hydraulic cylinder, to which working fluid discharged from the hydraulic pump is supplied through a discharge line, an operating selector valve for selectively providing and interrupting fluid communication into the discharge line between the hydraulic pump and the actuator, a controller for controlling the adjustable speed motor, and a pressure sensor for detecting the pressure of the discharge line for the hydraulic pump (see, for example, Patent Document 1).
The controller is configured to control the rotational speed of the adjustable speed motor so that the pressure of the discharge line detected by the pressure sensor and the flow rate thereof calculated from the rotational speed of the adjustable speed motor can be a pressure and a flow rate both lying on a predetermined target pressure-flow rate curve. In other words, the fluid pressure unit is configured to control by itself the pressure and flow rate of fluid discharged from the hydraulic pump without externally receiving any pressure command signal and flow rate command signal. This eliminates the need to externally input a pressure command signal or a flow rate command signal and dispenses with any input signal line, thereby saving the trouble of the operator inputting commands for the pressure or the flow rate and simplifying the wiring.    Patent Document 1: Unexamined Japanese Patent Publication No. 2001-90671